Seismic waves propagated and recorded at regional distances in eastern North America are being studies for possible use in discriminating between explosion and earthquake sources. This report deals with (a) the propagation characteristics of the regional seismic wave designated L sub g and (b) an evaluation of the usefulness of a particular ocean bottom seismograph system as an aid in discrimination of seismic sources at regional distances. Results of the study of the propagation characteristics of L sub g, with predominant frequencies of 1-3 hertz, is consistently the largest amplitude portion of the short period signal from the Eastern North American events studied. Analysis of the group velocity for each event studied shows a clustering of measurements in the 3.47 km/sec range for the earthquakes studied and a significantly lower 3.24 km/sec mean for measurements from the SALMON explosion. This lower value is believed to be the result of propagation path or source effects. When group velocity information was divided into two regions, E (h)--high group velocity (4.0-3.4 km/sec) energy--and E(l )--low group velocity (3.4-2.8 km/sec) energy, the ratios of these areas showed a discrimination between SALMON ((E(h)/E(l) .5) and the earthquakes ((E(h)/E(l).5). Phase velocity measurements made using records from Cumberland Plateau Seismic Observatory have a mean of 4.18 km/sec. Analysis of a second event also yields measurements in the 4.0-4.4 km/sec range.